I am looking for a pair of new production (meaning not expensive NOS) 6l6GC's that can HONESTLY withstand 500+ volts on the plates. The amp is a late 70's Fender Pro-Reverb with a b+ of around 500-512 volts, depending on biasing. I have tried Groove tubes, Mesa Boogies, Sovteks and Svetlanas and they all went to hell (red plates, meltdown, etc).

It appears the reissue Tung Sol's can withstand 550 volts. Anyone have experience with these?

How are your soldering and schematic-reading skills? If they're up to snuff, you might try these. The price is right and they're everything that SND claims and more. No problem with high plate voltages.

__________________
“The short explanation is always dull. It generally includes the word ‘just.’ The explanation only becomes beautiful when you immerse yourself in every nuance.”

hey-Hey!!!,
With the -GC version I have found dissipation far more important than voltage. I've run 6L6GC in my Dynaco Mk.III at ~520V and a full 30W of dissipation. At this level, grid circuit value, and dissipation limits are quite more than the usual tube-flavoured 'suggestion', much more like the ratings applied to silicon devices...

Make sure your amp isn't running them over the limits first.
cheers,
Douglas

I have used GC's (new production) and even with the bias at minimum (around -50 volts) they fail. They don't make em like they used to, I guess. I also read that JJ has a version rated at 550 plate. Anyone tried those?

Interestingly, the vintage Sylvanias that came with the amp when I bought it worked just fine. The only issue was that one broke and the other became microphonic , but those 6BG6's look good.

On the latest (Bassman 100) I used JJ 6L6GC and regretted it. They were'nt really well matched and 2 stopped working as a result of very minor physical taps. I had the amp upside down on the work bench. I pulled the tubes - as they released they moved maybe 1 inch (2.5 cm) and the glass domes rapped onto the rubberized antistatic mat on my work bench. Evebn so that was enough to kill them. Simply no current at all from 2 of the 4 output tubes when put back in. That meant I had to buy another quad.

The amp I did before that was a Twin Reverb, the 135W Ultralinear job, and I used Winged C Svetlana. This was an amp for a professional muso - and he loved them. They balanced perfectly and did'nt even blink at the B+ of +500V on anodes AND screens.

The one before that was a Vintage Bandmaster and I used Winged C Svets in it as well.

The Winged C Svetlana are little more expensive BUT worth it for their superior sound and reliability - PLUS their bases fit into those dingy Fender tube clamps - and they are cheaper than having to buy 2 quads from JJ to end up with one working quad.

Philips/ECG 6BG6GA's are tough and a heck of deal in my opinion. You'll just have to deal with the pin incompatibility and the end cap. I would hope the end cap won't rattle off from all th' vibratin'.